Traditionally, the non-volatile storage needs of computer systems were served by one or more disk drives locally attached to the systems. Operating systems maintained their own file management systems for the dedicated disk drives. Storage area networks evolved from the traditional dedicated memory architecture. A storage area network operates according to a client/server model. A storage area network may include one or more servers and a plurality of storage devices, typically disk drives. In addition, a storage area network may appear to a client computer system as a locally-attached storage device. A storage area network may allow a client to access data in units of blocks. Further, a storage area network may allow the sharing of data on two or more different computers, even if the computers employ different file management systems.
Another development is storage virtualization. A virtual storage device appears to a client as a logical storage location. The physical storage location or locations are hidden from the client. A virtual storage server handles the process of mapping data to physical locations. The storage virtualization paradigm may be incorporated into a storage area network.